VISUAL TESTING CORE ? SUMMARY Visual Testing Module. The Visual Testing module assesses visual function in rats, mice and other small animals by measuring the electroretinogram (ERG), the visual evoked potential (VEP), and the optokinetic response. Full-field (Ganzfeld flash) ERGs, multifocal ERGs, and pattern ERGs (pERGs) are used to evaluate retinal function, including the status of retinal ganglion cells as revealed by the pERG. VEPs and the optokinetic response (measured with an eye tracker) assess higher order visual function. The module is managed by a visual testing manager who maintains the test equipment, provides training to Core Grant investigators and staff on use of the equipment, and runs tests on experimental animals. A great savings in time and expense is realized by this module as investigators would otherwise would have to buy expensive visual testing equipment individually and train their staff in the use of the equipment.